Re: [Qemu-devel] [RFC qom-cpu v2 1/8] apic: remove apic_no from apic_init_common()

["Andreas Färber" <afaerber@suse.de>]

Am 10.09.2013 14:09, schrieb Igor Mammedov:
> On Tue, 10 Sep 2013 17:43:41 +0800
> Chen Fan <chen.fan.fnst@cn.fujitsu.com> wrote:
> 
>> the 'apic_no' is increased by one when initialize/create a vCPU each time,
>> which causes APICCommonState s->idx always is increased.
>> but if we want to re-add a vCPU after removing a vCPU, we need to re-use the
>> vacant s->idx which the corresponding vCPU had been removed. 
>> so we could use the unique cpu apic_id instead of the progressive s->idx.
>>
>> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
>> ---
>>  hw/intc/apic_common.c | 4 +---
>>  target-i386/cpu.c     | 1 +
>>  2 files changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
>> index a0beb10..5568621 100644
>> --- a/hw/intc/apic_common.c
>> +++ b/hw/intc/apic_common.c
>> @@ -289,13 +289,11 @@ static int apic_init_common(ICCDevice *dev)
>>      APICCommonState *s = APIC_COMMON(dev);
>>      APICCommonClass *info;
>>      static DeviceState *vapic;
>> -    static int apic_no;
>>      static bool mmio_registered;
>>  
>> -    if (apic_no >= MAX_APICS) {
>> +    if (s->idx >= MAX_APICS) {
>>          return -1;
>>      }
>> -    s->idx = apic_no++;
>>  
>>      info = APIC_COMMON_GET_CLASS(s);
>>      info->init(s);
>> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>> index 42c5de0..2b99683 100644
>> --- a/target-i386/cpu.c
>> +++ b/target-i386/cpu.c
>> @@ -2322,6 +2322,7 @@ static void x86_cpu_apic_create(X86CPU *cpu, Error **errp)
>>      /* TODO: convert to link<> */
>>      apic = APIC_COMMON(env->apic_state);
>>      apic->cpu = cpu;
>> +    apic->idx = env->cpuid_apic_id;
> earlier here we set:
>  qdev_prop_set_uint8(env->apic_state, "id", env->cpuid_apic_id);
> so apic->idx = env->cpuid_apic_id is redundant.
> 
> it would be better to search by apic->id and preferably replace O(MAX_APIC) scans with
> a faster approach since for TCG iqr delivery might be a hot path, dropping MAX_APIC
> altogether and using dynamic present APICs list.

Independent of that, the recent removal of X86_CPU() cast from
x86_env_get_cpu() should allow us to finally tackle the TODO above,
moving apic_state field from CPUX86State to X86CPU.

Andreas

> 
>>  }
>>  
>>  static void x86_cpu_apic_realize(X86CPU *cpu, Error **errp)
> 


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